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Vitamin D

Topic Contents

Vitamin D

Uses

What Are Star Ratings?

Our proprietary “Star-Rating” system was developed to help you easily understand the amount of scientific support behind each supplement in relation to a specific health condition. While there is no way to predict whether a vitamin, mineral, or herb will successfully treat or prevent associated health conditions, our unique ratings tell you how well these supplements are understood by the medical community, and whether studies have found them to be effective for other people.

For over a decade, our team has combed through thousands of research articles published in reputable journals. To help you make educated decisions, and to better understand controversial or confusing supplements, our medical experts have digested the science into these three easy-to-follow ratings. We hope this provides you with a helpful resource to make informed decisions towards your health and well-being.

3 Stars Reliable and relatively consistent scientific data showing a substantial health benefit.

2 Stars Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.

1 Star For an herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support.

This supplement has been used in connection with the following health conditions:

Used for	Why
3 Stars Crohn’s Disease 1,000 to 1,200 IU daily under medical supervision	Vitamin D malabsorption is common in Crohn’s and can lead to a deficiency of the vitamin. Supplementation can help prevent bone loss in cases of deficiency. Vitamin D malabsorption is common in Crohn’s¹ and can lead to a deficiency of the vitamin.² Successful treatment with vitamin D for osteomalacia (bone brittleness caused by vitamin D deficiency) triggered by Crohn’s disease has been reported.³ Another study found 1,000 IU per day of vitamin D prevented bone loss in people with Crohn’s, while an unsupplemented group experienced significant bone loss.⁴ In addition, in a double-blind trial, vitamin D supplementation (1,200 IU per day for 12 months) prevented relapses in patients with Crohn's disease in remission. The patients in that study had normal vitamin D status prior to receiving vitamin D supplementation.⁵ A doctor should be consulted to determine the right level of vitamin D for supplementation.
3 Stars Cystic Fibrosis 1,000 to 2,000 IU daily	The fat malabsorption associated with cystic fibrosis often leads to a deficiency of fat-soluble vitamins, such as vitamin D. Supplementation can help counteract the deficiency. The fat malabsorption associated with CF often leads to a deficiency of fat-soluble vitamins. Oral supplementation of these nutrients is considered crucial to maintaining good nutritional status.⁶ Current recommendations for supplementation are as follows: vitamin A , 5,000 to 10,000 IU/day; vitamin D , 1,000 to 2,000 IU/day; vitamin E , 100 to 300 IU/day; and vitamin K , 5 mg every three days. Of the water-soluble vitamins, only vitamin B12 is poorly absorbed in cystic fibrosis,⁷ and taking pancreatic enzymes helps prevent B12 deficiencies.⁸
3 Stars Osteoporosis 400 to 800 IU daily depending on age, sun exposure, and dietary sources	Vitamin D increases calcium absorption and helps make bones stronger. Vitamin D supplementation has reduced bone loss in women who don’t get enough of the vitamin from food and slowed bone loss in people with osteoporosis. It also works with calcium to prevent some musculoskeletal causes of falls and subsequent fractures. Vitamin D increases calcium absorption, and blood levels of vitamin D are directly related to the strength of bones.⁹ Mild deficiency of vitamin D is common in the fit, active elderly population and leads to an acceleration of age-related loss of bone mass and an increased risk of fracture.¹⁰ In double-blind research, vitamin D supplementation has reduced bone loss in women who consume insufficient vitamin D from food and slowed bone loss in people with osteoporosis.¹¹ ^{, 12} However, the effect of vitamin D supplementation on osteoporosis risk remains surprisingly unclear,¹³ ^{, 14} with some trials reporting little if any benefit.¹⁵ Moreover, trials reporting reduced risk of fracture have usually combined vitamin D with calcium supplementation,¹⁶ making it difficult to assess how much benefit is caused by supplementation with vitamin D alone.¹⁷ Impaired balance and increased body sway are important causes of falls in elderly people with osteoporosis.¹⁸ Vitamin D works with calcium to prevent some musculoskeletal causes of falls.¹⁹ In a double-blind trial, elderly women who were given 800 IU per day of vitamin D and 1,200 mg per day of calcium had a significantly lower rate of falls and subsequent fractures than did women given the same amount of calcium alone.²⁰ Vitamin D in the amount of 800 IU per day effectively prevented falls in a double-blind study of elderly nursing home residents, but lower amounts were ineffective.²¹ Despite inconsistency in the research, many doctors recommend 400 to 800 IU per day of supplemental vitamin D, depending upon dietary intake and exposure to sunlight. One trial studying postmenopausal women combined hormone replacement therapy with magnesium (600 mg per day), calcium (500 mg per day), vitamin C , B vitamins , vitamin D, zinc, copper, manganese, boron , and other nutrients for an eight- to nine-month period.²² In addition, participants were told to avoid processed foods, limit protein intake, emphasize vegetable over animal protein, and limit consumption of salt, sugar, alcohol, coffee, tea, chocolate, and tobacco. Bone density increased a remarkable 11%, compared to only 0.7% in women receiving hormone replacement alone.
3 Stars Rickets Consult a qualified healthcare practitioner	Vitamin D supplements may be helpful in preventing and treating rickets. Vitamin D and calcium supplements should be used to treat rickets only if a medical professional has diagnosed rickets and has also determined the cause is a nutritional deficiency. Amounts needed to treat rickets should be determined by a doctor and will depend on the age, weight, and condition of the child. For prevention of rickets, 400 IU of vitamin D per day is considered reasonable. Doctors often suggest 1,600 IU per day for treating rickets caused by a lack of dietary vitamin D.
2 Stars Asthma 1,200 IU per day for 15 to 17 weeks	A study of Japanese children found that daily supplementation with vitamin D during the winter months significantly reduced the amount of times the children experienced asthma attacks. In a double-blind study of Japanese children (average age, ten years), supplementation with 1,200 IU per day of vitamin D for 15 to 17 weeks during the winter significantly reduced the incidence of asthma attacks compared with a placebo.²³
2 Stars Burns 200 to 600 IU day in cases of extensive burns	People with a history of an extensive burn might benefit from vitamin D supplementation, since the skin may not be as effective at manufacturing vitamin D from sunlight. Burns affecting a large proportion of the body may result in vitamin D deficiency²⁴, potentially increasing the risk of osteoporosis, which is a frequent long-term consequence of severe burns.²⁵ Vitamin D deficiency may result from the inability of previously burned skin to manufacture vitamin D after exposure to sunlight. People with a history of an extensive burn might benefit from vitamin D supplementation.
2 Stars Celiac Disease Consult a qualified healthcare practitioner	Malabsorption-induced vitamin D deficiency can lead to bone weakening in people with celiac disease. Supplementing with vitamin D may help increase bone density. The malabsorption that occurs in celiac disease can lead to multiple nutritional deficiencies. The most common nutritional problems in people with celiac disease include deficiencies of essential fatty acids, iron , vitamin D , vitamin K , calcium , magnesium , and folic acid .²⁶ Zinc malabsorption also occurs frequently in celiac disease²⁷ and may result in zinc deficiency, even in people who are otherwise in remission.²⁸ People with newly diagnosed celiac disease should be assessed for nutritional deficiencies by a doctor. Celiac patients who have not yet completely recovered should supplement with a high-potency multivitamin-mineral . Some patients may require even higher amounts of some of these vitamins and minerals—an issue that should be discussed with their healthcare practitioner. Evidence of a nutrient deficiency in a celiac patient is a clear indication for supplementation with that nutrient. After commencement of a gluten-free diet, overall nutritional status gradually improves. However, deficiencies of some nutrients may persist, even in people who are strictly avoiding gluten. For example, magnesium deficiency was found in 8 of 23 adults with celiac disease who had been following a gluten-free diet and were symptom-free. When these adults were supplemented with magnesium for two years, their bone mineral density increased significantly.²⁹ Malabsorption-induced depletion of vitamin D can lead to osteomalacia (defective bone mineralization) in people with celiac disease.³⁰ Although supplementation with vitamin D appears to increase bone density, the excess risk of bone fracture may not be entirely eliminated.
2 Stars Depression 400 to 800 IU daily	Some studies have shown that supplementing with vitamin D leads to improved mood. Blood levels of vitamin D (measured as 25-hydroxyvitamin D) have been found to be significantly lower in people with depression than in healthy people.³¹ Vitamin D supplementation may be associated with elevations in mood. In a double-blind trial, healthy people were given 400–800 IU per day of vitamin D3, or no vitamin D3, for five days during late winter. Results showed that vitamin D3 significantly enhanced positive mood and there was some evidence of a reduction in negative mood compared to a placebo.³² In another double-blind trial, people without depression took 600 IU of vitamin D along with 1,000 mg of calcium , or a placebo, twice daily for four weeks.³³ Compared to the placebo, combined vitamin D and calcium supplementation produced significant elevations in mood that persisted at least one week after supplementation was discontinued.
2 Stars Hypertension 800 IU daily	In one trial, women with low blood levels of vitamin D who were given calcium supplement plus vitamin D experienced significantly reduced systolic blood pressure. In a double-blind trial, women with low blood levels of vitamin D (measured as 25-hydroxyvitamin D3) were given a calcium supplement, plus either 800 IU of vitamin D per day or a placebo for eight weeks. Compared with the placebo, vitamin D significantly reduced systolic blood pressure by an average of 9.3%, but did not affect diastolic blood pressure.³⁴
2 Stars Influenza 800 IU per day for two years; then 2,000 IU per day after that	In one study, long-term vitamin D supplementation for three years significantly reduced flu and cold symptoms. In a double-blind study, African Americans who received vitamin D supplements for three years had significantly fewer symptoms of influenza or colds, when compared with women who received a placebo. The amount of vitamin D was 800 IU per day for the first two years, followed by 2,000 IU per day for one year.³⁵
2 Stars Influenza and Children 1,200 IU per day for 15 to 17 weeks	A study of Japanese children found that daily supplementation with vitamin D during the winter months significantly reduced the amount of times the children developed the flu. In a double-blind study of Japanese children (average age, ten years), supplementation with 1,200 IU per day of vitamin D for 15 to 17 weeks during the winter significantly reduced the incidence of influenza infections by 42%, compared with a placebo.³⁶
2 Stars Low Back Pain Refer to label instructions	In people with muscle pain associated with vitamin D deficiency, supplementing with the vitamin may improve pain. Some studies have found that vitamin D levels are lower in people with back pain than in healthy people.³⁷ ^{, 38} In patients with muscle pain associated with vitamin D deficiency, vitamin D supplementation has resulted in improvement in the pain.³⁹
2 Stars Prostate Cancer 2,000 IU daily	Taken under a doctor's supervision, vitamin D might help reduce pain and slow down disease progression. Where sun exposure is low, the rate of prostate cancer has been reported to be high.⁴⁰ ^{, 41} In the body, vitamin D is changed into a hormone with great activity. This activated vitamin D causes “cellular differentiation”—essentially the opposite of cancer. In a preliminary trial, 7 of 16 men who had prostate cancer that had spread to bone and who had been unresponsive to conventional treatment were found to have evidence of vitamin D deficiency.⁴² All 16 were given 2,000 IU of vitamin D per day for 12 weeks, and levels of pain were recorded for 14 of these men. Vitamin D supplementation led to reduced pain in 4 of the 14 men, and 6 showed evidence of increased strength.⁴³ Those with vitamin D deficiency were more likely to respond, compared with those who were not deficient.⁴⁴ People taking 2,000 IU per day of Vitamin D should be supervised by a doctor. In another preliminary study, men with prostate cancer that had relapsed after surgery or radiation therapy were treated with 2,000 IU of vitamin D per day for nine months. In approximately half of the men, the prostate-specific antigen (PSA) level decreased, suggesting that the progression of the disease had been halted or reversed; this decrease was sustained for 5 to 17 months.⁴⁵ In addition, the study was done in Toronto, Canada, where the amount of sunlight is limited and vitamin D status tends to be low. It is not known whether vitamin D supplementation would be as effective in geographical regions such as the Southern United States, where the amount of sunlight is greater.
2 Stars Seasonal Affective Disorder Refer to label instructions	Supplementing with vitamin D may improve mood and well-being, especially among people with low levels of the vitamin. Vitamin D is well known for its effects on helping to maintain normal calcium levels, but it also exerts influence on the brain, spinal cord, and hormone-producing tissues of the body that may be important in the regulation of mood.⁴⁶ A double-blind study found that mood improved in healthy people without SAD who received 400 or 800 IU per day of vitamin D for five days in late winter.⁴⁷ In another study, people with SAD were randomly assigned to receive either 100,000 IU of vitamin D one time only or two hours of bright-light therapy every day for one month. After one month, researchers observed a significant improvement in depression in the group that received vitamin D, but not in the group given light therapy.⁴⁸ However, a one-year study of healthy postmenopausal women found that supplementation with 400 IU of vitamin D per day did not prevent the mood decline that often occurs in the winter.⁴⁹ Certain differences in these studies might account for the different results: In the study in which vitamin D was beneficial, the participants suffered from SAD and their pretreatment vitamin D blood levels tended to be low. In the negative study, the participants did not have SAD, and their pretreatment vitamin D blood levels were higher. Although additional research needs to be done, the available evidence suggests that people with SAD who have marginal or deficient vitamin D levels might benefit from supplementation. This treatment should be supervised by a doctor to assure that the amount of vitamin D used is high enough to be effective, but not so high as to cause adverse effects.
2 Stars Tension Headache (Calcium) 1,000 to 1,500 mg per day (plus the same amount of calcium)	In preliminary research, people with chronic tension-type headaches who were also suffering from severe vitamin D deficiency experienced an improvement in their symptoms after supplementing with vitamin D and calcium. In a preliminary trial, eight patients had chronic tension-type headache in association with severe vitamin D deficiency. In each case, the headaches resolved after treatment with vitamin D3 (1,000 to 1,500 IU per day) and calcium (1,000 to 1,500 mg per day).⁵⁰
2 Stars Type 1 Diabetes Consult a qualified healthcare practitioner	Vitamin D is needed to maintain adequate insulin levels, and supplementing with it may reduce the risk of developing type 1 diabetes. Vitamin D is needed to maintain adequate blood levels of insulin .⁵¹ Vitamin D receptors have been found in the pancreas where insulin is made and some, but not all preliminary evidence suggests that supplementation might reduce the risk of developing type 1 diabetes.⁵² ^{, 53} Vitamin D supplementation may also slow the decline of pancreatic function in people with newly diagnosed type 1 diabetes who have not yet suffered an extensive loss of pancreatic function.⁵⁴ Not enough is known about optimal amounts of vitamin D for people with diabetes, and high amounts of vitamin D can be toxic. Therefore, people with diabetes considering vitamin D supplementation should talk with a doctor and have their vitamin D status assessed.
2 Stars Type 2 Diabetes 1,332 IU daily	Vitamin D is needed to maintain adequate insulin levels, and supplementing with it may improve blood sugar control in people with type 2 diabetes. Vitamin D is needed to maintain adequate blood levels of insulin.⁵⁵ Vitamin D receptors have been found in the pancreas where insulin is made. Some,⁵⁶ ^{, 57} ^{, 58} but not all,⁵⁹ ^{, 60} preliminary trials have found that supplementation can improve some measures of blood sugar control in people with type 2 diabetes. In addition, in a preliminary trial supplementation with about 2,000 IU of vitamin D per day for three months significantly improved pain by almost 50% in patients with diabetic neuropathy.⁶¹ Not enough is known about optimal amounts of vitamin D for people with diabetes, and high amounts of vitamin D can be toxic; therefore, people with diabetes considering vitamin D supplementation should talk with a doctor and have their vitamin D status assessed.
1 Star Alcohol Withdrawal Refer to label instructions	If deficient, supplementing with this vitamin may help prevent bone loss and muscle weakness. Although the incidence of B-complex deficiencies is known to be high in alcoholics, the incidence of other vitamin deficiencies remains less clear.⁶³ Nonetheless, deficiencies of vitamin A , vitamin D , vitamin E , and vitamin C are seen in many alcoholics. While some reports have suggested it may be safer for alcoholics to supplement with beta-carotene instead of vitamin A,⁶⁴ potential problems accompany the use of either vitamin A or beta-carotene in correcting the deficiency induced by alcoholism.⁶⁵ These problems result in part because the combinations of alcohol and vitamin A or alcohol and beta-carotene appear to increase potential damage to the liver. Thus, vitamin A-depleted alcoholics require a doctor’s intervention, including supplementation with vitamin A and beta-carotene accompanied by assessment of liver function. Supplementing with vitamin C, on the other hand, appears to help the body rid itself of alcohol.⁶⁶ Some doctors recommend 1 to 3 grams per day of vitamin C.
1 Star Amenorrhea and Osteoporosis (Calcium) Refer to label instructions	Despite the lack of evidence that calcium and vitamin D supplements alone are helpful to amenorrheic women, they are still generally recommended to prevent the added burden of calcium and vitamin D deficiency from further contributing to bone loss. A preliminary trial showed that bone loss occurred over a one-year period in amenorrheic exercising women despite daily supplementation with 1,200 mg of calcium and 400 IU of vitamin D .⁶⁷ In a controlled study of amenorrheic nursing women, who ordinarily experience brief bone loss that reverses when menstruation returns, bone loss was not prevented by a multivitamin supplement providing 400 IU of vitamin D along with 500 mg twice daily of calcium or placebo.⁶⁸ Despite the lack of evidence that calcium and vitamin D supplements alone are helpful to amenorrheic women, they are still generally recommended to prevent the added burden of calcium and vitamin D deficiency from further contributing to bone loss.⁶⁹ Amounts typically recommended are 1,200 to 1,500 mg calcium and 400 to 800 IU vitamin D daily.
1 Star Breast Cancer Refer to label instructions	Vitamin D from supplements and from exposure to the sun both appear to protect against breast cancer. Breast cancer rates have been reported to be relatively high in areas of low exposure to sunlight.⁷⁰ Sunlight triggers the formation of vitamin D in the skin, which can be activated in the liver and kidneys into a hormone with great activity. This activated form of vitamin D causes “cellular differentiation”—essentially the opposite of cancer. The following evidence indicates that vitamin D might have a protective role against breast cancer: Synthetic vitamin D-like molecules have prevented the equivalent of breast cancer in animals.⁷¹ Activated vitamin D appears to have antiestrogenic activity.⁷² Both sunlight and dietary exposure to vitamin D have correlated with a reduced risk of breast cancer.⁷³ ^{, 74} Activated vitamin D comes in several forms. One of them—1,25 dihydroxycholecalciferol—is an exact duplicate of the hormone made in the human body. The following preliminary, non-clinical evidence supports the idea that activated vitamin D may be of help to some breast cancer patients: In combination with tamoxifen , a synthetic, activated-vitamin D-like molecule has inhibited the growth of breast cancer cells in test tube research.⁷⁵ Synthetic vitamin D-like molecules induce tumor cell death in breast cancer cells.⁷⁶ Activated vitamin D suppresses the growth of human cancer cells transplanted into animals.⁷⁷ In test tube research, activated vitamin D has increased the anticancer action of chemotherapy.⁷⁸ In a preliminary trial, activated vitamin D was applied topically to the breast, once per day for six weeks, in 19 patients with breast cancer.⁷⁹ Of the 14 patients who completed the trial, three showed a large reduction in tumor size, and one showed a minor improvement. Those who responded had tumors that contained receptors for activated vitamin D. However, other preliminary reports have not found that high levels of these receptors consistently correlate with a better outcome.⁸⁰ ^{, 81} ^{, 82} With a doctor’s prescription, compounding pharmacists can put activated vitamin D, a hormone, into a topical ointment. Due to potential toxicity, use of this hormone, even topically, requires careful monitoring by a physician. Standard vitamin D supplements are unlikely to duplicate the effects of activated vitamin D in women with breast cancer. The patients in the breast cancer trial all had locally advanced disease.
1 Star Cardiac Arrhythmia Refer to label instructions	One case report described relief from a type of arrhythmia after supplementing with vitamin D. One case of long-standing sick-sinus syndrome (another type of arrhythmia) was reported to resolve upon supplementation with 800 IU per day of vitamin D prescribed for an unrelated condition. However, it was not clear from that report whether the improvement was due to the vitamin D.⁸³ More research is needed.
1 Star Colon Cancer Refer to label instructions	People who take vitamin D supplements have been shown to be at low risk for colon cancer. Ultraviolet light from sun exposure increases the risk of skin cancers and melanoma. Nonetheless, where sun exposure is low, rates of several cancers have been reported to be high.⁸⁴ ^{, 85} ^{, 86} An association between greater sun exposure and a reduced risk of colon cancer has appeared in some,⁸⁷ but not all, studies.⁸⁸ In preliminary reports, people who take vitamin D supplements have been reported to be at low risk for colon cancer, though the differences between supplement takers and others might have been due to chance.⁸⁹ ^{, 90} More research is needed to determine whether vitamin D supplements may be useful in connection with the prevention of colon cancer.
1 Star Dysmenorrhea Refer to label instructions	In a double-blind trial, women with dysmenorrhea received a placebo or a single administration of a large amount of vitamin D, which appeared to significantly diminish menstrual pain. This should only be done under doctor supervision. In a double-blind trial, women with dysmenorrhea received a placebo or a single administration of a large amount of vitamin D (300,000), five days before the expected onset of the next menstrual period. During the next two menstrual periods, menstrual pain was significantly lower in the vitamin D group than in the placebo group.⁹¹ Such a large amount of vitamin D should be given only under the supervision of a doctor. Further research is needed to determine whether daily supplementation of a smaller amount (such as 800 to 2,000 IU per day) would have a similar beneficial effect.
1 Star Migraine Headache Refer to label instructions	Taking large amounts of the combination of calcium and vitamin D has been reported to produce a marked reduction in the incidence of migraines in several women. Taking large amounts of the combination of calcium (1,000 to 2,000 mg per day) and vitamin D has been reported to produce a marked reduction in the incidence of migraines in several women.⁹² ^{, 93} However, the amount of vitamin D given to these women (usually 50,000 IU once a week), can cause adverse reactions, particularly when used in combination with calcium. This amount of vitamin D should be used only under medical supervision. Doctors often recommend that people take 800 to 1,200 mg of calcium and 400 IU of vitamin D per day. However, it is not known whether theses amounts would have an effect on migraines.
1 Star Multiple Sclerosis Refer to label instructions	Studies suggest that vitamin D may help reduce the number of MS attacks and may protect against the development of the disease. Animal studies have demonstrated that vitamin D can prevent an experimental form of multiple sclerosis. In humans, striking geographical differences in the prevalence of multiple sclerosis suggest that sun exposure (which promotes the synthesis of vitamin D) may protect against the development of the disease. In addition, higher blood levels of vitamin D are associated with a lower risk of developing MS.⁹⁴ However, no clinical trials have been done to determine whether increasing vitamin D intake or sunlight exposure would prevent MS. In a preliminary trial, treatment with very large amounts of vitamin D (more than 10,000 IU per day) was associated with a decrease in the number of relapses in patients with MS; however, the decrease was not statistically significant.⁹⁵ In a double-blind study of patients with MS, a large amount of vitamin D (approximately 10,000 IU per day), when compared with a moderate amount (1,000 IU per day), resulted in a significant increase in the relapse rate and in the degree of disability.⁹⁶ Based on the available evidence, large amounts of vitamin D cannot be recommended as a treatment for MS. Additional research is needed to determine whether moderate amounts of vitamin D would be beneficial.
1 Star Parkinson’s Disease Refer to label instructions	Vitamin D deficiency is common in Parkinson’s disease and may increase the risk of hip fracture due to osteoporosis. This risk may be reduced by taking vitamin D. Vitamin D deficiency is common in Parkinson’s disease. People with Parkinson’s often get insufficient sun exposure and have reduced levels of activity that adversely affect calcium metabolism.⁹⁷ Low vitamin D levels in Parkinson’s disease have been reported to increase the risk of hip fracture due to osteoporosis .⁹⁸ This risk has been significantly reduced with the use of synthetic, activated vitamin D—a prescription drug.⁹⁹ Whether the same effect could be achieved with supplemental vitamin D remains unknown, though some doctors recommend 400–1,000 IU vitamin D per day. People with Parkinson’s disease may wish to discuss the use of synthetic activated vitamin D with a healthcare professional.
1 Star Urinary Incontinence Refer to label instructions	Higher blood levels of vitamin D are associated with lower risk of urinary incontinence in women. Vitamin D may be important for normal muscle function, including muscles that help control urinary continence.¹⁰⁰ ^{, 101} Higher blood levels of vitamin D are associated with lower risk of urinary incontinence in women, according to one preliminary study.¹⁰² Controlled trials are needed to determine whether vitamin D supplements can help prevent or treat urinary incontinence.
1 Star Vitiligo Refer to label instructions	When used in combination with sun exposure, a form of vitamin D called calcipotriol may be effective in stimulating repigmentation in children with vitiligo. When used topically in combination with sun exposure, a pharmaceutical form of vitamin D , called calcipotriol, may be effective in stimulating repigmentation in children with vitiligo. In a preliminary study, children applied a cream containing calcipotriol daily and exposed themselves to sunlight for 10–15 minutes the following morning.¹⁰³ After 11 months, marked to complete repigmentation occurred in 55% of the children, moderate repigmentation occurred in 22%, and little or no improvement was seen in 22%. None of the children developed new areas of vitiligo. The first evidence of repigmentation occurred within 6 to 12 weeks in the majority of the children. All participants tolerated the cream well, with approximately 17% complaining of mild, transient skin irritation. Calcipotriol is a prescription medication to be used only under the supervision of a doctor. It is not known whether vitamin D as a dietary supplement has any effect on vitiligo.
0 Stars Sunburn (Vitamin A) Refer to label instructions	Antioxidants may protect the skin from sunburn due to free radical –producing ultraviolet rays.¹⁰⁴ Combinations of 1,000 to 2,000 IU per day of vitamin E and 2,000 to 3,000 mg per day of vitamin C , but neither given alone, have a significant protective effect against ultraviolet rays, according to double-blind studies.¹⁰⁵ ^{, 106} ^{, 107} Oral synthetic beta-carotene alone was not found to provide effective protection when given in amounts of 15 mg per day or for only a few weeks’ time in larger amounts of 60 to 90 mg per day, but it has been effective either in very large (180 mg per day) amounts or in smaller amounts (30 mg per day) in combination with topical sunscreen.¹⁰⁸ ^{, 109} ^{, 110} ^{, 111} ^{, 112} Natural sources of beta-carotene or other carotenoids have been more consistently shown to protect against sunburn. One controlled study found that taking a supplement of natural carotenoids (almost all of which was beta-carotene) in daily amounts of 30 mg, 60 mg, and 90 mg gave progressively more protection against ultraviolet rays.¹¹³ In another controlled study, either 24 mg per day of natural beta-carotene or 24 mg per day of a carotenoid combination of equal amounts beta-carotene, lutein , and lycopene helped protect skin from ultraviolet rays.¹¹⁴ A preliminary study compared synthetic lycopene (10.1 mg per day), a natural tomato extract containing 9.8 mg of lycopene per day plus additional amounts of other carotenoids, and a solubilized tomato drink (designed to increase lycopene absorption) containing 8.2 mg of lycopene plus additional amounts of other carotenoids. After 12 weeks, only the two tomato-based products were shown to give significant protection against burning by ultraviolet light.¹¹⁵ Still other trials have tested combinations of several antioxidants . One preliminary study found that a daily combination of beta-carotene (6 mg), lycopene (6 mg), vitamin E (15 IU), and selenium for seven weeks protected against ultraviolet light.¹¹⁶ However, a double-blind trial of a combination of smaller amounts of several carotenoids , vitamins C and E, selenium, and proanthocyanidins did not find significant UV protection compared with placebo.¹¹⁷ Similarly, in a controlled trial, a combination of selenium, copper , and vitamins was found to be ineffective.¹¹⁸ It should be noted that while oral protection from sunburn has been demonstrated with several types of antioxidants , the degree of protection (typically less than an SPF of 2) is much less than that provided by currently available topical sunscreens. On the other hand, these modest effects will provide some added protection to skin areas where sunscreen is also used and will give a small amount of protection to sun-exposed areas where sunscreen is not applied. However, oral protection from sunburn is not instantaneous; maximum effects are not reached until these antioxidants have been used for about eight to ten weeks.¹¹⁹ ^{, 120}

How It Works

How to Use It

People who get plenty of sun exposure do not require supplemental vitamin D, since sunlight increases vitamin D synthesis when it strikes bare skin. Although the recommended dietary allowance for vitamin D is 200 IU per day for adults, there is some evidence that elderly people need 800 to 1,000 IU per day for maximum effects on preserving bone density and preventing fractures.¹²¹ ^{, 122} ^{, 123} ^{, 124} Sun-deprived people should take no less than 600 IU per day and ideally around 1,000 IU per day.¹²⁵ ^{, 126}

Where to Find It

Cod liver oil is an excellent dietary source of vitamin D, as are vitamin D-fortified foods. Traces of vitamin D are found in egg yolks and butter. However, the majority of vitamin D in the body is created during a chemical reaction that starts with sunlight exposure to the skin. Cholecalciferol (vitamin D3) is the animal form of this vitamin.

Possible Deficiencies

In adults, vitamin D deficiency may result in a softening of the bones known as osteomalacia . This condition is treated with vitamin D, sometimes in combination with calcium supplements. Osteomalacia should be diagnosed, and its treatment monitored, by a doctor. In people of any age, vitamin D deficiency causes abnormal bone formation. In addition, vitamin D deficiency can cause muscle weakness, which improves with vitamin D supplementation.¹²⁷ Vitamin D deficiency occurs more commonly following winter, owing to restricted sunlight exposure during that season. Living in an area with a lot of atmospheric pollution, which can block the sun's ultraviolet rays, also appears to increase the risk of vitamin D deficiency.¹²⁸ ¹²⁹

Vitamin D deficiency is more common in strict vegetarians (who avoid vitamin D-fortified dairy foods), dark-skinned people,¹³⁰ alcoholics, and people with liver or kidney disease. People with liver and kidney disease can make vitamin D but cannot activate it.

Vitamin D deficiency is more common in people suffering from intestinal malabsorption , which may have occurred following previous intestinal surgeries, or from celiac disease .¹³¹ People with insufficient pancreatic function (e.g., those with pancreatitis or cystic fibrosis ) tend to be deficient in vitamin D. Vitamin D deficiency is also common in individuals with hyperthyroidism (Graves' disease), particularly women.¹³²

In children, vitamin D deficiency is called rickets and causes a bowing of bones not seen in adults with vitamin D deficiency. Vitamin D deficiency is common among people with hyperparathyroidism, a condition in which the parathyroid gland is overactive. In a study of 124 people with mild hyperparathyroidism, vitamin D levels were below normal in 7% of them and suboptimal in 53% of them.¹³³ Vitamin D deficiency is also common in men with advanced prostate cancer . In one study, 44% of 16 men with advanced prostate cancer had decreased blood levels of vitamin D.¹³⁴

One in seven adults has been reported to be deficient in vitamin D.¹³⁵ In one study, 42% of hospitalized patients under age 65 were reported to be vitamin D deficient.¹³⁶ In this same study, 37% of the people were found to be deficient in vitamin D, despite the fact they were eating the currently recommended amount of this nutrient. Vitamin D deficiency is particularly common among the elderly. Age-related decline in vitamin D status may be due to reduced absorption, transport, or liver metabolism of vitamin D.¹³⁷

Interactions

Interactions with Supplements, Foods, & Other Compounds

Vitamin D increases both calcium and phosphorus absorption and has also been reported to increase aluminum absorption.¹³⁸

Interactions with Medicines

Certain medicines interact with this supplement.

What Are Drug Interactions

Types of interactions: Beneficial Adverse Check

Replenish Depleted Nutrients

Carbamazepine

Though research results vary, long-term use of anticonvulsant drugs appears to interfere with vitamin D activity,¹⁴¹ which might lead to softening of bones ( osteomalacia ). One study showed that blood levels of vitamin D in males taking anticonvulsants were lower than those found in men who were not taking seizure medication.¹⁴² In a controlled study, bone strength improved in children taking anticonvulsant drugs who were supplemented with the activated form of vitamin D and 500 mg per day of calcium for nine months.¹⁴³ Some research suggests that differences in exposure to sunlight—which normally increases blood levels of vitamin D—might explain why some studies have failed to find a beneficial effect of vitamin D supplementation. In one controlled study, blood vitamin D levels in children taking anticonvulsants were dramatically lower in winter months than in summer months.¹⁴⁴ Another study of 450 people in Florida taking anticonvulsants found that few had drug-induced bone disease.¹⁴⁵ Consequently, people taking anticonvulsant drugs who do not receive adequate sunlight should supplement with 400 IU of vitamin D each day to help prevent osteomalacia.
Cholestyramine

Bile acid sequestrants may prevent absorption of folic acid and the fat-soluble vitamins A , D , E , and K .¹⁵¹ ^{, 152} Other medications and vitamin supplements should be taken one hour before or four to six hours after bile acid sequestrants for optimal absorption.¹⁵³ Animal studies suggest calcium and zinc may also be depleted by taking cholestyramine.¹⁵⁴
Cimetidine

Cimetidine may reduce vitamin D activation by the liver.¹⁵⁵ Lab tests can measure activated vitamin D levels in the blood. Forms of vitamin D that do not require liver activation are available, but only by prescription.
Colesevelam

Bile acid sequestrants may prevent absorption of folic acid and the fat-soluble vitamins A , D , E , and K .¹⁵⁶ ^{, 157} Other medications and vitamin supplements should be taken one hour before or four to six hours after bile acid sequestrants for optimal absorption.¹⁵⁸ Animal studies suggest calcium and zinc may also be depleted by taking cholestyramine.¹⁵⁹
Colestipol

Bile acid sequestrants, including colestipol, may prevent absorption of folic acid and the fat-soluble vitamins A , D , E , K .¹⁶⁰ ^{, 161} People taking colestipol should consult with their doctor about vitamin malabsorption and supplementation. People should take other drugs and vitamin supplements one hour before or four to six hours after colestipol to improve absorption.¹⁶²

Animal studies suggest calcium and zinc may be depleted by taking cholestyramine, another bile acid sequestrant. ¹⁶³ Whether these same interactions would occur with colestipol is not known.
Cortisone

Oral corticosteroids have been found to increase urinary loss of vitamin K , vitamin C , selenium , and zinc .¹⁶⁴ ^{, 165} The importance of these losses is unknown.
Dexamethasone

Oral corticosteroids reduce absorption of calcium¹⁶⁶ and interfere with the activation and metabolism of the vitamin,¹⁶⁷ ^{, 168} ^{, 169} ^{, 170} increasing the risk of bone loss. Doctors can measure levels of activated vitamin D (called 1,25 dihydroxycholecalciferol) to determine whether a deficiency exists; if so, activated vitamin D is only available by prescription. A study of rheumatoid arthritis patients treated with low amounts of prednisone found that those who received 1,000 mg of calcium per day plus 500 IU of vitamin D per day for two years experienced no bone loss during that time period.¹⁷¹ An analysis of properly conducted trials concluded that supplementation with vitamin D and calcium was more effective than placebo or calcium alone in protecting against corticosteroid-induced osteoporosis .¹⁷² Most doctors recommend 1,000 mg of calcium and 400–800 IU vitamin D per day for the prevention of osteoporosis.
Felbamate

Though research results vary, long-term use of anticonvulsant drugs appears to interfere with vitamin D activity,¹⁷³ which might lead to softening of bones ( osteomalacia ). One study showed that blood levels of vitamin D in males taking anticonvulsants were lower than those found in men who were not taking seizure medication.¹⁷⁴ In a controlled study, bone strength improved in children taking anticonvulsant drugs who were supplemented with the activated form of vitamin D and 500 mg per day of calcium for nine months.¹⁷⁵ Some research suggests that differences in exposure to sunlight—which normally increases blood levels of vitamin D—might explain why some studies have failed to find a beneficial effect of vitamin D supplementation. In one controlled study, blood vitamin D levels in children taking anticonvulsants were dramatically lower in winter months than in summer months.¹⁷⁶ Another study of 450 people in Florida taking anticonvulsants found that few had drug-induced bone disease.¹⁷⁷ Consequently, people taking anticonvulsant drugs who do not receive adequate sunlight should supplement with 400 IU of vitamin D each day to help prevent osteomalacia.
Flurbiprofen

Elevated calcium and vitamin D blood levels are commonly found in people with sarcoidosis. In one individual with sarcoidosis, taking flubiprofen lowered elevated blood calcium levels, but did not alter the concentration of vitamin D.¹⁸³ One controlled study showed that flurbiprofen reduced blood levels of vitamin D in people with frequent calcium kidney stones .¹⁸⁴ Further research is needed to determine whether flurbiprofen reduces blood calcium and vitamin D levels in healthy people.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Heparin

Heparin may interfere with activation of vitamin D in the body.¹⁸⁶ Osteoporosis (thinning of the bone) has been reported in patients who received high amounts of heparin for several months.¹⁸⁷ Osteopenia (decreased bone density) has been reported in women who received heparin therapy during pregnancy .¹⁸⁸ ^{, 189}
Hydrocodone

Normally, the active form of vitamin D increases the absorption of calcium into the body. In a 45-year-old woman with sarcoidosis, taking hydroxychloroquine blocked the formation of active vitamin D, which helped normalize elevated blood levels of calcium in this case.¹⁹⁰ Whether hydroxychloroquine has this effect in people who don’t have sarcoidosis or elevated calcium is unknown. Until controlled research explores this interaction more thoroughly, people taking hydroxychloroquine might consider having their vitamin D and/or calcium status monitored by a health practitioner.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Isoniazid

Isoniazid may interfere with the activity of other nutrients, including vitamin B3 (niacin) , vitamin B12 , vitamin D , and vitamin E , folic acid , calcium , and magnesium .¹⁹¹ ^{, 192} Supplementation with vitamin B6 is thought to help prevent isoniazid-induced niacin deficiency; however, small amounts of vitamin B6 (e.g. 10 mg per day) appear to be inadequate in some cases.¹⁹³ People should consider using a daily multivitamin-mineral supplement during isoniazid therapy.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Levetiracetam

Though research results vary, long-term use of anticonvulsant drugs appears to interfere with vitamin D activity,¹⁹⁴ which might lead to softening of bones ( osteomalacia ). One study showed that blood levels of vitamin D in males taking anticonvulsants were lower than those found in men who were not taking seizure medication.¹⁹⁵ In a controlled study, bone strength improved in children taking anticonvulsant drugs who were supplemented with the activated form of vitamin D and 500 mg per day of calcium for nine months.¹⁹⁶ Some research suggests that differences in exposure to sunlight—which normally increases blood levels of vitamin D—might explain why some studies have failed to find a beneficial effect of vitamin D supplementation. In one controlled study, blood vitamin D levels in children taking anticonvulsants were dramatically lower in winter months than in summer months.¹⁹⁷ Another study of 450 people in Florida taking anticonvulsants found that few had drug-induced bone disease.¹⁹⁸ Consequently, people taking anticonvulsant drugs who do not receive adequate sunlight should supplement with 400 IU of vitamin D each day to help prevent osteomalacia.
Mineral Oil

Mineral oil has interfered with the absorption of many nutrients, including beta-carotene , calcium , phosphorus , potassium , and vitamins A , D , K , and E in some,²¹² but not all,²¹³ research. Taking mineral oil on an empty stomach may reduce this interference. It makes sense to take a daily multivitamin-mineral supplement two hours before or after mineral oil. It is important to read labels, because many multivitamins do not contain vitamin K or contain inadequate (less than 100 mcg per day) amounts.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Neomycin

Neomycin can decrease absorption or increase elimination of many nutrients, including calcium , carbohydrates, beta-carotene , fats, folic acid , iron , magnesium , potassium , sodium, and vitamin A , vitamin B12 , vitamin D , and vitamin K .²¹⁴ ^{, 215} Surgery preparation with oral neomycin is unlikely to lead to deficiencies. It makes sense for people taking neomycin for more than a few days to also take a multivitamin-mineral supplement.
Orlistat

In one well-controlled study, taking orlistat for six months resulted in reduced blood levels of vitamins A and D, though levels for most individuals remained within the normal range. However, a few people developed levels low enough to require supplementation.²¹⁶ Other studies have shown that taking orlistat had no affect on blood vitamin A levels.²¹⁷ ^{, 218} Although additional research is needed, the current evidence suggests that individuals taking orlistat for more than six months should supplement with vitamins A and D.
Oxcarbazepine

Though research results vary, long-term use of anticonvulsant drugs appears to interfere with vitamin D activity,²²⁴ which might lead to softening of bones ( osteomalacia ). One study showed that blood levels of vitamin D in males taking anticonvulsants were lower than those found in men who were not taking seizure medication.²²⁵ In a controlled study, bone strength improved in children taking anticonvulsant drugs who were supplemented with the activated form of vitamin D and 500 mg per day of calcium for nine months.²²⁶ Some research suggests that differences in exposure to sunlight—which normally increases blood levels of vitamin D—might explain why some studies have failed to find a beneficial effect of vitamin D supplementation. In one controlled study, blood vitamin D levels in children taking anticonvulsants were dramatically lower in winter months than in summer months.²²⁷ Another study of 450 people in Florida taking anticonvulsants found that few had drug-induced bone disease.²²⁸ Consequently, people taking anticonvulsant drugs who do not receive adequate sunlight should supplement with 400 IU of vitamin D each day to help prevent osteomalacia.
Phenytoin

Though research results vary, long-term use of anticonvulsant drugs appears to interfere with vitamin D activity,²²⁹ which might lead to softening of bones ( osteomalacia ). One study showed that blood levels of vitamin D in males taking anticonvulsants were lower than those found in men who were not taking seizure medication.²³⁰ In a controlled study, bone strength improved in children taking anticonvulsant drugs who were supplemented with the activated form of vitamin D and 500 mg per day of calcium for nine months.²³¹ Some research suggests that differences in exposure to sunlight—which normally increases blood levels of vitamin D—might explain why some studies have failed to find a beneficial effect of vitamin D supplementation. In one controlled study, blood vitamin D levels in children taking anticonvulsants were dramatically lower in winter months than in summer months.²³² Another study of 450 people in Florida taking anticonvulsants found that few had drug-induced bone disease.²³³ Consequently, people taking anticonvulsant drugs who do not receive adequate sunlight should supplement with 400 IU of vitamin D each day to help prevent osteomalacia.
Prednisolone

Oral corticosteroids have been found to increase urinary loss of vitamin K , vitamin C , selenium , and zinc .²³⁶ ^{, 237} The importance of these losses is unknown.
Prednisone

Oral corticosteroids have been found to increase urinary loss of vitamin K , vitamin C , selenium , and zinc .²³⁸ ^{, 239} The importance of these losses is unknown.
Primidone

Though research results vary, long-term use of anticonvulsant drugs appears to interfere with vitamin D activity,²⁴⁰ which might lead to softening of bones ( osteomalacia ). One study showed that blood levels of vitamin D in males taking anticonvulsants were lower than those found in men who were not taking seizure medication.²⁴¹ In a controlled study, bone strength improved in children taking anticonvulsant drugs who were supplemented with the activated form of vitamin D and 500 mg per day of calcium for nine months.²⁴² Some research suggests that differences in exposure to sunlight—which normally increases blood levels of vitamin D—might explain why some studies have failed to find a beneficial effect of vitamin D supplementation. In one controlled study, blood vitamin D levels in children taking anticonvulsants were dramatically lower in winter months than in summer months.²⁴³ Another study of 450 people in Florida taking anticonvulsants found that few had drug-induced bone disease.²⁴⁴ Consequently, people taking anticonvulsant drugs who do not receive adequate sunlight should supplement with 400 IU of vitamin D each day to help prevent osteomalacia.
Topiramate

Though research results vary, long-term use of anticonvulsant drugs appears to interfere with vitamin D activity,²⁵³ which might lead to softening of bones ( osteomalacia ). One study showed that blood levels of vitamin D in males taking anticonvulsants were lower than those found in men who were not taking seizure medication.²⁵⁴ In a controlled study, bone strength improved in children taking anticonvulsant drugs who were supplemented with the activated form of vitamin D and 500 mg per day of calcium for nine months.²⁵⁵ Some research suggests that differences in exposure to sunlight—which normally increases blood levels of vitamin D—might explain why some studies have failed to find a beneficial effect of vitamin D supplementation. In one controlled study, blood vitamin D levels in children taking anticonvulsants were dramatically lower in winter months than in summer months.²⁵⁶ Another study of 450 people in Florida taking anticonvulsants found that few had drug-induced bone disease.²⁵⁷ Consequently, people taking anticonvulsant drugs who do not receive adequate sunlight should supplement with 400 IU of vitamin D each day to help prevent osteomalacia.
Zonisamide

Though research results vary, long-term use of anticonvulsant drugs appears to interfere with vitamin D activity,²⁶³ which might lead to softening of bones ( osteomalacia ). One study showed that blood levels of vitamin D in males taking anticonvulsants were lower than those found in men who were not taking seizure medication.²⁶⁴ In a controlled study, bone strength improved in children taking anticonvulsant drugs who were supplemented with the activated form of vitamin D and 500 mg per day of calcium for nine months.²⁶⁵ Some research suggests that differences in exposure to sunlight—which normally increases blood levels of vitamin D—might explain why some studies have failed to find a beneficial effect of vitamin D supplementation. In one controlled study, blood vitamin D levels in children taking anticonvulsants were dramatically lower in winter months than in summer months.²⁶⁶ Another study of 450 people in Florida taking anticonvulsants found that few had drug-induced bone disease.²⁶⁷ Consequently, people taking anticonvulsant drugs who do not receive adequate sunlight should supplement with 400 IU of vitamin D each day to help prevent osteomalacia.

Reduce Side Effects

Anastrozole

In a double-blind study, vitamin D supplementation relieved drug-induced musculoskeletal symptoms in women with breast cancer who were taking anastrozole.¹³⁹ The amount of vitamin D used was relatively large (up to 50,000 IU of vitamin D2 once a week) and is potentially toxic. Vitamin D therapy in people taking anastrozole should therefore be prescribed and monitored by a doctor.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Atorvastatin

In a preliminary trial, supplementation with vitamin D appeared to prevent muscle-related side effects in patients taking statin drugs.¹⁴⁰ The amount of vitamin D used in this study was very large (up to 50,000 IU twice a week) and potentially toxic. People taking statin drugs should consult with their doctor regarding how much vitamin D can be taken.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Carbamazepine

Though research results vary, long-term use of anticonvulsant drugs appears to interfere with vitamin D activity,¹⁴⁶ which might lead to softening of bones ( osteomalacia ). One study showed that blood levels of vitamin D in males taking anticonvulsants were lower than those found in men who were not taking seizure medication.¹⁴⁷ In a controlled study, bone strength improved in children taking anticonvulsant drugs who were supplemented with the activated form of vitamin D and 500 mg per day of calcium for nine months.¹⁴⁸ Some research suggests that differences in exposure to sunlight—which normally increases blood levels of vitamin D—might explain why some studies have failed to find a beneficial effect of vitamin D supplementation. In one controlled study, blood vitamin D levels in children taking anticonvulsants were dramatically lower in winter months than in summer months.¹⁴⁹ Another study of 450 people in Florida taking anticonvulsants found that few had drug-induced bone disease.¹⁵⁰ Consequently, people taking anticonvulsant drugs who do not receive adequate sunlight should supplement with 400 IU of vitamin D each day to help prevent osteomalacia.
Felbamate

Though research results vary, long-term use of anticonvulsant drugs appears to interfere with vitamin D activity,¹⁷⁸ which might lead to softening of bones ( osteomalacia ). One study showed that blood levels of vitamin D in males taking anticonvulsants were lower than those found in men who were not taking seizure medication.¹⁷⁹ In a controlled study, bone strength improved in children taking anticonvulsant drugs who were supplemented with the activated form of vitamin D and 500 mg per day of calcium for nine months.¹⁸⁰ Some research suggests that differences in exposure to sunlight—which normally increases blood levels of vitamin D—might explain why some studies have failed to find a beneficial effect of vitamin D supplementation. In one controlled study, blood vitamin D levels in children taking anticonvulsants were dramatically lower in winter months than in summer months.¹⁸¹ Another study of 450 people in Florida taking anticonvulsants found that few had drug-induced bone disease.¹⁸² Consequently, people taking anticonvulsant drugs who do not receive adequate sunlight should supplement with 400 IU of vitamin D each day to help prevent osteomalacia.
Fluvastatin

In a preliminary trial, supplementation with vitamin D appeared to prevent muscle-related side effects in patients taking statin drugs¹⁸⁵ The amount of vitamin D used in this study was very large (up to 50,000 IU twice a week) and potentially toxic. People taking statin drugs should consult with their doctor regarding how much vitamin D can be taken.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Levetiracetam

Though research results vary, long-term use of anticonvulsant drugs appears to interfere with vitamin D activity,¹⁹⁹ which might lead to softening of bones ( osteomalacia ). One study showed that blood levels of vitamin D in males taking anticonvulsants were lower than those found in men who were not taking seizure medication.²⁰⁰ In a controlled study, bone strength improved in children taking anticonvulsant drugs who were supplemented with the activated form of vitamin D and 500 mg per day of calcium for nine months.²⁰¹ Some research suggests that differences in exposure to sunlight—which normally increases blood levels of vitamin D—might explain why some studies have failed to find a beneficial effect of vitamin D supplementation. In one controlled study, blood vitamin D levels in children taking anticonvulsants were dramatically lower in winter months than in summer months.²⁰² Another study of 450 people in Florida taking anticonvulsants found that few had drug-induced bone disease.²⁰³ Consequently, people taking anticonvulsant drugs who do not receive adequate sunlight should supplement with 400 IU of vitamin D each day to help prevent osteomalacia.
Lovastatin

In a preliminary trial, supplementation with vitamin D appeared to prevent muscle-related side effects in patients taking statin drugs.²⁰⁴ The amount of vitamin D used in this study was very large (up to 50,000 IU twice a week) and potentially toxic. People taking statin drugs should consult with their doctor regarding how much vitamin D can be taken.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Methylprednisolone

Oral corticosteroids reduce absorption of calcium²⁰⁵ and interfere with the activation and metabolism of the vitamin,²⁰⁶ ^{, 207} ^{, 208} ^{, 209} increasing the risk of bone loss. Doctors can measure levels of activated vitamin D (called 1,25 dihydroxycholecalciferol) to determine whether a deficiency exists; if so, activated vitamin D is only available by prescription. A study of rheumatoid arthritis patients treated with low amounts of prednisone found that those who received 1,000 mg of calcium per day plus 500 IU of vitamin D per day for two years experienced no bone loss during that time period.²¹⁰ An analysis of properly conducted trials concluded that supplementation with vitamin D and calcium was more effective than placebo or calcium alone in protecting against corticosteroid-induced osteoporosis .²¹¹ Most doctors recommend 1,000 mg of calcium and 400–800 IU vitamin D per day for the prevention of osteoporosis.
Oxcarbazepine

Though research results vary, long-term use of anticonvulsant drugs appears to interfere with vitamin D activity,²¹⁹ which might lead to softening of bones ( osteomalacia ). One study showed that blood levels of vitamin D in males taking anticonvulsants were lower than those found in men who were not taking seizure medication.²²⁰ In a controlled study, bone strength improved in children taking anticonvulsant drugs who were supplemented with the activated form of vitamin D and 500 mg per day of calcium for nine months.²²¹ Some research suggests that differences in exposure to sunlight—which normally increases blood levels of vitamin D—might explain why some studies have failed to find a beneficial effect of vitamin D supplementation. In one controlled study, blood vitamin D levels in children taking anticonvulsants were dramatically lower in winter months than in summer months.²²² Another study of 450 people in Florida taking anticonvulsants found that few had drug-induced bone disease.²²³ Consequently, people taking anticonvulsant drugs who do not receive adequate sunlight should supplement with 400 IU of vitamin D each day to help prevent osteomalacia.
Pitavastatin

In a preliminary trial, supplementation with vitamin D appeared to prevent muscle-related side effects in patients taking statin drugs.²³⁴ The amount of vitamin D used in this study was very large (up to 50,000 IU twice a week) and potentially toxic. People taking statin drugs should consult with their doctor regarding how much vitamin D can be taken.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Pravastatin

In a preliminary trial, supplementation with vitamin D appeared to prevent muscle-related side effects in patients taking statin drugs.²³⁵ The amount of vitamin D used in this study was very large (up to 50,000 IU twice a week) and potentially toxic. People taking statin drugs should consult with their doctor regarding how much vitamin D can be taken.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Primidone

Though research results vary, long-term use of anticonvulsant drugs appears to interfere with vitamin D activity,²⁴⁵ which might lead to softening of bones ( osteomalacia ). One study showed that blood levels of vitamin D in males taking anticonvulsants were lower than those found in men who were not taking seizure medication.²⁴⁶ In a controlled study, bone strength improved in children taking anticonvulsant drugs who were supplemented with the activated form of vitamin D and 500 mg per day of calcium for nine months.²⁴⁷ Some research suggests that differences in exposure to sunlight—which normally increases blood levels of vitamin D—might explain why some studies have failed to find a beneficial effect of vitamin D supplementation. In one controlled study, blood vitamin D levels in children taking anticonvulsants were dramatically lower in winter months than in summer months.²⁴⁸ Another study of 450 people in Florida taking anticonvulsants found that few had drug-induced bone disease.²⁴⁹ Consequently, people taking anticonvulsant drugs who do not receive adequate sunlight should supplement with 400 IU of vitamin D each day to help prevent osteomalacia.
Rosuvastatin

In a preliminary trial, supplementation with vitamin D appeared to prevent muscle-related side effects in patients taking statin drugs.²⁵⁰ The amount of vitamin D used in this study was very large (up to 50,000 IU twice a week) and potentially toxic. People taking statin drugs should consult with their doctor regarding how much vitamin D can be taken.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Simvastatin

In a preliminary trial, supplementation with vitamin D appeared to prevent muscle-related side effects in patients taking statin drugs.²⁵¹ The amount of vitamin D used in this study was very large (up to 50,000 IU twice a week) and potentially toxic. People taking statin drugs should consult with their doctor regarding how much vitamin D can be taken.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Topiramate

Though research results vary, long-term use of anticonvulsant drugs appears to interfere with vitamin D activity,²⁵⁸ which might lead to softening of bones ( osteomalacia ). One study showed that blood levels of vitamin D in males taking anticonvulsants were lower than those found in men who were not taking seizure medication.²⁵⁹ In a controlled study, bone strength improved in children taking anticonvulsant drugs who were supplemented with the activated form of vitamin D and 500 mg per day of calcium for nine months.²⁶⁰ Some research suggests that differences in exposure to sunlight—which normally increases blood levels of vitamin D—might explain why some studies have failed to find a beneficial effect of vitamin D supplementation. In one controlled study, blood vitamin D levels in children taking anticonvulsants were dramatically lower in winter months than in summer months.²⁶¹ Another study of 450 people in Florida taking anticonvulsants found that few had drug-induced bone disease.²⁶² Consequently, people taking anticonvulsant drugs who do not receive adequate sunlight should supplement with 400 IU of vitamin D each day to help prevent osteomalacia.
Zonisamide

Though research results vary, long-term use of anticonvulsant drugs appears to interfere with vitamin D activity,²⁶⁸ which might lead to softening of bones ( osteomalacia ). One study showed that blood levels of vitamin D in males taking anticonvulsants were lower than those found in men who were not taking seizure medication.²⁶⁹ In a controlled study, bone strength improved in children taking anticonvulsant drugs who were supplemented with the activated form of vitamin D and 500 mg per day of calcium for nine months.²⁷⁰ Some research suggests that differences in exposure to sunlight—which normally increases blood levels of vitamin D—might explain why some studies have failed to find a beneficial effect of vitamin D supplementation. In one controlled study, blood vitamin D levels in children taking anticonvulsants were dramatically lower in winter months than in summer months.²⁷¹ Another study of 450 people in Florida taking anticonvulsants found that few had drug-induced bone disease.²⁷² Consequently, people taking anticonvulsant drugs who do not receive adequate sunlight should supplement with 400 IU of vitamin D each day to help prevent osteomalacia.

Support Medicine

Sodium Fluoride

Collagen is a protein that is used in many areas of the body for structural support. One test tube study showed that the active form of vitamin D, 1,25 dihydroxycholecalciferol, increased the production of a certain type of collagen when it was combined with fluoride.²⁵² Controlled research is needed to determine whether taking 1,25 dihydroxycholecalciferol with sodium fluoride might promote beneficial collagen growth.

Reduces Effectiveness

none

Potential Negative Interaction

Verapamil

Vitamin D may interfere with the effectiveness of verapamil.²⁷³ People taking verapamil should ask their doctor before using vitamin D-containing supplements.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Warfarin

In 1975, a single letter to the Journal of the American Medical Association suggested that vitamin D increases the activity of anticoagulants and that this interaction could prove dangerous.²⁷⁴ However, there have been no other reports of such an interaction, even though tens of millions of people are taking multivitamins that contain vitamin D. Most doctors typically do not tell patients taking anticoagulant medications to avoid vitamin D.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Explanation Required

Allopurinol

Individuals with gout have low blood concentration of the active form of vitamin D (1,25 dihydroxycholecalciferol), and allopurinol corrects this problem.²⁷⁵
Bendroflumethiazide

The reduction in urinary calcium loss resulting from treatment with thiazide diuretics is due primarily to changes in kidney function and may also be due, in part, to changes in vitamin D metabolism.²⁷⁶ However, there is no evidence to suggest that people taking diuretics have different requirements for vitamin D.
Chlorothiazide

The reduction in urinary calcium loss resulting from treatment with thiazide diuretics is due primarily to changes in kidney function and may also be due, in part, to changes in vitamin D metabolism.²⁷⁷ However, there is no evidence to suggest that people taking diuretics have different requirements for vitamin D.
Chlorthalidone

The reduction in urinary calcium loss resulting from treatment with thiazide diuretics is due primarily to changes in kidney function and may also be due, in part, to changes in vitamin D metabolism.²⁷⁸ However, there is no evidence to suggest that people taking diuretics have different requirements for vitamin D.
Estradiol

In controlled studies, the addition of 300 IU per day of vitamin D3 (cholecalciferol) did not improve the bone-preserving or fracture-preventing effects of hormone replacement with estradiol plus a progestin (a synthetic form of progesterone) in postmenopausal women without osteoporosis .²⁷⁹ ^{, 280} However, in a controlled study of osteoporotic women, only those receiving both hormone replacement and vitamin D had increases in bone density of the hip; no improvement occurred in the hip with hormones alone.²⁸¹ More research is needed to determine conclusively when vitamin D is important to add to hormone replacement.
Gabapentin

Though research results vary, long-term use of anticonvulsant drugs appears to interfere with vitamin D activity, which might lead to softening of bones ( osteomalacia ). One study showed that blood levels of vitamin D in males taking anticonvulsants were lower than those found in men who were not taking seizure medication.²⁸² In a controlled study, bone strength improved in children taking anticonvulsant drugs who were supplemented with the activated form of vitamin D and 500 mg per day of calcium for nine months.²⁸³ Some research suggests that differences in exposure to sunlight—which normally increases blood levels of vitamin D—might explain why some studies have failed to find a beneficial effect of vitamin D supplementation. In one controlled study, blood vitamin D levels in children taking anticonvulsants were dramatically lower in winter months than in summer months.²⁸⁴ Another study of 450 people in Florida taking anticonvulsants found that few had drug-induced bone disease.²⁸⁵ Consequently, people taking anticonvulsant drugs who do not receive adequate sunlight should supplement with 400 IU of vitamin D each day to help prevent osteomalacia.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Hydrochlorothiazide

The reduction in urinary calcium loss resulting from treatment with thiazide diuretics is due primarily to changes in kidney function and may also be due, in part, to changes in vitamin D metabolism.²⁸⁶ However, there is no evidence to suggest that people taking diuretics have different requirements for vitamin D.
Hydroflumethiazide

The reduction in urinary calcium loss resulting from treatment with thiazide diuretics is due primarily to changes in kidney function and may also be due, in part, to changes in vitamin D metabolism.²⁸⁷ However, there is no evidence to suggest that people taking diuretics have different requirements for vitamin D.
Indapamide

The reduction in urinary calcium loss resulting from treatment with thiazide diuretics is due primarily to changes in kidney function and may also be due, in part, to changes in vitamin D metabolism.²⁸⁸ However, there is no evidence to suggest that people taking diuretics have different requirements for vitamin D.
Medroxyprogesterone

In a study of postmenopausal women, treatment with estrogen alone increased vitamin D blood levels, whereas estrogen plus medroxyprogesterone lowered vitamin D back to the level seen without estrogen use.²⁸⁹ This outcome might suggest that medroxyprogesterone interferes with beneficial effects estrogen may have on vitamin D metabolism and vitamin D supplementation would be called for. However, some research has not found the addition of vitamin D to estrogen/progestin combinations to be helpful.²⁹⁰ Therefore, while many doctors recommend 400 IU vitamin D to women taking estrogen/progestin combination hormone products, the efficacy of such supplementation has not been proven.
Methyclothiazide

The reduction in urinary calcium loss resulting from treatment with thiazide diuretics is due primarily to changes in kidney function and may also be due, in part, to changes in vitamin D metabolism.²⁹¹ However, there is no evidence to suggest that people taking diuretics have different requirements for vitamin D.
Metolazone

The reduction in urinary calcium loss resulting from treatment with thiazide diuretics is due primarily to changes in kidney function and may also be due, in part, to changes in vitamin D metabolism.¹⁰ However, there is no evidence to suggest that people taking diuretics have different requirements for vitamin D.
Phenobarbital

Though research results vary, long-term use of anticonvulsant drugs appears to interfere with vitamin D activity, which might lead to softening of bones ( osteomalacia ). One study showed that blood levels of vitamin D in males taking anticonvulsants were lower than those found in men who were not taking seizure medication.²⁹² In a controlled study, bone strength improved in children taking anticonvulsant drugs who were supplemented with the activated form of vitamin D and 500 mg per day of calcium for nine months.²⁹³ Some research suggests that differences in exposure to sunlight—which normally increases blood levels of vitamin D—might explain why some studies have failed to find a beneficial effect of vitamin D supplementation. In one controlled study, blood vitamin D levels in children taking anticonvulsants were dramatically lower in winter months than in summer months.²⁹⁴ Another study of 450 people in Florida taking anticonvulsants found that few had drug-induced bone disease.²⁹⁵ Consequently, people taking anticonvulsant drugs who do not receive adequate sunlight should supplement with 400 IU of vitamin D each day to help prevent osteomalacia.
Polythiazide

The reduction in urinary calcium loss resulting from treatment with thiazide diuretics is due primarily to changes in kidney function and may also be due, in part, to changes in vitamin D metabolism.²⁹⁶ However, there is no evidence to suggest that people taking diuretics have different requirements for vitamin D.
Risedronate

Short-term treatment with risedronate in people with hyperparathydoidism—a disorder characterized by high blood levels of calcium—resulted in lower calcium blood levels.²⁹⁷ Additional research is needed to determine whether people taking risedronate for Paget’s disease might develop low blood calcium levels. As a precaution, people with Paget’s disease should take supplemental calcium and vitamin D if dietary intake is inadequate. However, taking risedronate at the same time as calcium supplements reduces absorption of the drug.²⁹⁸ Therefore, people taking risedronate for Paget’s disease should take calcium supplements an hour before or two hours after taking the drug.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Trichlormethiazide

The reduction in urinary calcium loss resulting from treatment with thiazide diuretics is due primarily to changes in kidney function and may also be due, in part, to changes in vitamin D metabolism.²⁹⁹ However, there is no evidence to suggest that people taking diuretics have different requirements for vitamin D.
Valproate

Though research results vary, long-term use of anticonvulsant drugs appears to interfere with vitamin D activity, which might lead to softening of bones ( osteomalacia ). One study showed that blood levels of vitamin D in males taking anticonvulsants were lower than those found in men who were not taking seizure medication.³⁰⁰ In a controlled study, bone strength improved in children taking anticonvulsant drugs who were supplemented with the activated form of vitamin D and 500 mg per day of calcium for nine months.³⁰¹ Some research suggests that differences in exposure to sunlight—which normally increases blood levels of vitamin D—might explain why some studies have failed to find a beneficial effect of vitamin D supplementation. In one controlled study, blood vitamin D levels in children taking anticonvulsants were dramatically lower in winter months than in summer months.³⁰² Another study of 450 people in Florida taking anticonvulsants found that few had drug-induced bone disease.³⁰³ Consequently, people taking anticonvulsant drugs who do not receive adequate sunlight should supplement with 400 IU of vitamin D each day to help prevent osteomalacia.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

The Drug-Nutrient Interactions table may not include every possible interaction. Taking medicines with meals, on an empty stomach, or with alcohol may influence their effects. For details, refer to the manufacturers’ package information as these are not covered in this table. If you take medications, always discuss the potential risks and benefits of adding a supplement with your doctor or pharmacist.

Side Effects

People with hyperparathyroidism should not take vitamin D without consulting a physician. People with sarcoidosis should not supplement with vitamin D, unless a doctor has determined that their calcium levels are not elevated. Too much vitamin D taken for long periods of time may lead to headaches, weight loss , and kidney stones . Rarely, excessive vitamin D may even lead to deafness, blindness, increased thirst, increased urination, diarrhea , irritability, children’s failure to gain weight, or death.

Most people take 400 IU per day, a safe amount for adults. Some researchers believe that amounts up to 10,000 IU per day are safe for the average healthy adult, although adverse effects may occur even at lower levels among people with hypersensitivity to vitamin D (e.g. hyperparathyroidism).³⁰⁴ In fact, of all published cases of vitamin D toxicity for which a vitamin D amount is known, only one occurred at a level of intake under 40,000 IU per day.³⁰⁵ Nevertheless, people wishing to take more than 1,000 IU per day for long periods of time should consult a physician. People should remember the total daily intake of vitamin D includes vitamin D from fortified milk and other fortified foods, cod liver oil , supplements that contain vitamin D, and sunlight. People who receive adequate sunlight exposure do not need as much vitamin D in their diet as do people who receive minimal sunlight exposure.

Some,³⁰⁶ but not all,³⁰⁷ research suggests that vitamin D may slightly raise blood levels of cholesterol in humans.

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Last Review: 11-07-2012

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Complementary Medicine - Cam

Topic Contents

Vitamin D

Uses

This supplement has been used in connection with the following health conditions:

How It Works

How to Use It

Where to Find It

Possible Deficiencies

Interactions

Interactions with Supplements, Foods, & Other Compounds

Interactions with Medicines

Replenish Depleted Nutrients

Reduce Side Effects

Support Medicine

Reduces Effectiveness

Potential Negative Interaction

Explanation Required

Side Effects

Side Effects

Related Information

References